The field of art to which this invention pertains is aqueous dispersions of synthetic polymers, particularly aqueous dispersions of synthetic polymers prepared by polymerizing ethylenically unsaturated monomers in water in the presence of a protective colloid.
The use of protective colloids as stabilizers for aqueous dispersions and emulsions is well known in the art. Protective colloids are water-soluble materials which form colloidal solutions. Such materials include starch, casein, glue, shellac, polyvinyl alcohol, sodium polyacrylate, methylcellulose, hydroxyethyl cellulose and the like. U.S. Pat. No. 2,998,400 sets forth a number of protective colloids which have been used in aqueous polymer dispersion preparations among which are polyacrylic acid, saccharide of polygalacturonic acid, gum arabic, hydroxyethyl cellulose, gelatine, citrus, pectin, starch, sulfonated-carboxylated starch, polyvinyl alcohol, sodium carboxymethyl cellulose, propylene glycol alginate gum tragacanth, polyacrylamide, and vinyl methyl ether-maleic anhydride copolymer and its half amide. The use of polyacrylic acid as a protective colloid is described in U.S. Pat. No. 2,671,065. Hydroxyalkyl galactomannans as protective colloids are described in U.S. Pat. No. 3,551,366.
U.S. Pat. No. 3,700,624 discloses the use of certain polyacrylate esters in an emulsion polymerization. However, the polyacrylate esters are not utilized following a transesterification of alcoholysis reaction, and no free hydroxyl groups are disclosed as being present in the product added to the emulsion. Finally, the product disclosed in this patent is added in its monomeric, rather than polymeric, form. U.S. Pat. No. 3,957,711 discloses the use of hydroxyacrylates or methacrylates as protective colloids. However, the emulsions of the instant invention exhibit improved adhesion and abrasion resistance properties, compared to these prior art emulsions.